1. Field of the Invention
This invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device with high mechanical strength.
2. Description of the Related Art
In general, a liquid crystal display (LCD) device used for a computer such as a portable computer or for a portable display is shown in FIG. 1. Referring to FIG. 1, the LCD device 10 includes a liquid crystal panel 100, a back light unit 101, and a driving circuit board 102. The back light unit 101 is composed of a luminescent lamp 104, a lamp housing 106, a light guide 108, a reflector 110 reflecting the incident light from the horizontal direction to the vertical direction, a protection sheet 112 contacting the light guide 108, a first prism sheet 114 and a second prism sheet 116 set on the protecting sheet 112, a diffuser 118 diffusing the light from the first and second prisms 114 and 116 to a viewing area 120 of the liquid crystal panel 100 with a certain viewing angle, and a housing 122 supporting these elements. The liquid crystal display device 10 also comprises a frame 124 coupled to the housing 122 for holding the liquid crystal panel 100 and back light unit 101.
Referring to FIG. 2, the liquid crystal display device 10 is usually combined with, for example, a notebook computer (not shown) as an output screen via a rear case 130 and a front case 134. The housing 122 of the LCD device 10 is mounted to the rear case 130 and the front case 134 using fastening elements, like screws 132. The front case 134 has a blank area adjusted to the viewing area.
FIG. 3a is a cross-sectional view taken from the line 3axe2x80x943a of FIG. 2. As shown, the frame 124 of the LCD device 10 has a plurality of holes 138 defined therein, and the housing 122 has a plurality of projections 136 for snap fitting into the holes 138 of the frame 124. The projections 136 of the housing 122 are engaged with the holes 138 of the frame 124 such that the housing 122 and the frame 124 are combined with each other.
Typically, as shown in FIG. 2, there is no hole formed in the central part 140 of the longer sides 142 of the frame 124 thereby acquiring a higher mechanical strength. Therefore, as shown in FIG. 3b, the central part of the housing 122 (corresponding to the central part 140 of the frame 124) is flat without any projection provided thereon. However, when the liquid crystal display device 10 is subjected to environment tests, especially the vibration test, stress is generally maximum at the central part 140 of the longer sides 142 of the frame 124 thereby causing unacceptable deformation at the central part 140
Accordingly, there exists a need in the art for a liquid crystal display device which overcomes, or at least reduces the above-mentioned problems of the prior art.
Therefore, it is an object of the present invention to provide a liquid crystal display device with high mechanical strength, particularly in the central portion of the longer side thereof.
To achieve the above listed and other objects, the present invention provides a liquid crystal display device mainly comprising a liquid crystal panel, a back light unit, a housing and a frame. The liquid crystal panel has opposing upper and lower surfaces. The back light unit is disposed under the lower surface of the liquid crystal panel and joined with it. The housing supports the back light unit and has a wall erected around the back light unit. The frame has a first portion covering at least one edge of the upper surface of the liquid crystal panel and a second portion coupled to the wall of the housing.
According to a first preferred embodiment of the present invention, the housing has at least one projection formed at the wall and the second portion of the frame is pressed by the projection such that the first portion of the frame is curved and concave toward the upper surface of the liquid crystal panel. Preferably, the second portion of the frame is curved and concave to touch the upper surface of the liquid crystal panel. Preferably, the projection is integrally formed with the housing.
According to a second preferred embodiment of the present invention, the second portion of the frame has at least one projection protruded in a direction toward the wall of the housing and the projection of the frame is pressed by the wall of the housing such that the first portion of the frame is curved and concave toward the upper surface of the liquid crystal panel and preferably touches the liquid crystal panel. It is preferred that the projection is integrally formed with the frame. Alternatively, the projection may be formed by press operation applied to the second portion of the frame.
Preferably, the projection is formed in the central part of the longer portion of the wall or the longer side of the second portion of the frame such that the first portion of the frame is curved in the central part of the longer side thereof. This significantly reinforces and stabilizes the structure of the frame and improves the mechanical strength of the frame, particularly in the central portion of the longer side thereof
It is preferred that the projection is chamfered to facilitate assembly of the frame and the housing.